Divide Array in Sets of K Consecutive Numbers

Given an array of integers nums and a positive integer k, find whether it's possible to divide this array into sets of k consecutive numbers Return True if its possible otherwise return False.

Example 1:

Input: nums = [1,2,3,3,4,4,5,6], k = 4
Output: true
Explanation: Array can be divided into [1,2,3,4] and [3,4,5,6].

Example 2:

Input: nums = [3,2,1,2,3,4,3,4,5,9,10,11], k = 3
Output: true
Explanation: Array can be divided into [1,2,3] , [2,3,4] , [3,4,5] and [9,10,11].

Example 3:

Input: nums = [3,3,2,2,1,1], k = 3
Output: true

Example 4:

Input: nums = [1,2,3,4], k = 3
Output: false
Explanation: Each array should be divided in subarrays of size 3.

Constraints:

• 1 <= nums.length <= 10^5

• 1 <= nums[i] <= 10^9

• 1 <= k <= nums.length

class Solution {
    public boolean isPossibleDivide(int[] nums, int k) {
        if (nums == null || nums.length % k != 0)
            return false;
        // Frequency map
        Map<Integer, Integer> map = new HashMap<>();
        for (int num : nums)
            map.put(num, map.getOrDefault(num, 0) + 1);

        for (int num : nums) {
            if (!map.containsKey(num))
                continue;
            // find the smallest value in current streak
            while (map.containsKey(num))
                num--;
            // Taking all the possible streaks of size k
            int start = num + 1, next = -1;
            // next holds the start of another streak in this continuous chain
            while (true) {
                for (int i = 0; i < k; i++) {
                    // a broken streak, return false.
                    if (!map.containsKey(start + i))
                        return false;
                    int frequency = map.get(start + i);
                    if (frequency == 1)
                        map.remove(start + i);
                    else {
                        map.put(start + i, frequency - 1);
                        if (next == -1)
                            next = start + i;
                    }
                }
                // end of current streak
                if (next == -1)
                    break;

                start = next;
                next = -1;
            }
        }
        return true;
    }
}